JohnD wrote:neufer wrote:I do know differently, John. Differently is a friend of mine.
If Io was lying on the surface of Jupiter its shadow would be directly under it
as viewed from Earth (~ 3.6º off the Sun-Jupiter axis).
http://space.jpl.nasa.gov/cgi-bin/wspac ... 1&showac=1
If Io was just one Jupiter radius above the surface of Jupiter
its shadow would be ~ 3.6º east longitude on Jupiter as viewed from Earth (~ 3.6º off the Sun-Jupiter axis).
Since Io is ~ 5 Jupiter radii above the surface of Jupiter
its shadow is ~ 18º east longitude on Jupiter as viewed from Earth (~ 3.6º off the Sun-Jupiter axis).
Thank you neufer! I now have a different perspective of your view.
But not the relevance of your link, which shows the Inner System
from Jupiter.
Can that view be adapted to show, even animate, the Earth view of Jupiter?
JOhn
The perspective was to show the ~ 3.6º angle between the Earth & the Sun as seen from Jupiter.
One can also approximate the angle by remembering that
the Earth moves ~ 1º daily in it's orbit about the Sun
and this was 16 days before opposition so it is ~ 16º.
From Jupiter at 5.2 AU that Earth orbital angle appears to be only ~ 16º/(5.2-1) = ~ 3.8º .
[Since Jupiter is orbiting as well once every 12 years
(such that Earth passes Jupiter only 11 times in 12 years)
this reduces to ~ 3.8º x 11/12 = 3.5º.]
The (shadowless) view of Jupiter from Earth shows the position on Io, itself, on Nov. 17 00:00UT:
http://space.jpl.nasa.gov/cgi-bin/wspac ... 1&showac=1
The view of Jupiter
from the Sun indicates the position on
Io's shadow on Nov. 17 00:00UT:
http://space.jpl.nasa.gov/cgi-bin/wspac ... 1&showac=1